2010-04-27

The kill-ring is emacs' implementation of a copy-paste-clipboard. As
expected, it's more powerful than what most other editors offer - but at the
same time, it may be a bit hard to use. We already discussed the kill-ring
in the Emacs-Fu prehistory.

One of the more powerful features of the emacs kill-ring is that is allows for
multiple entries to be saved there. You can then retrieve those older
entries by using prefix arguments, that is: C-y will retrieve the last
item from the kill-ring, while M-nC-y will retrieve the nth last
stretch of 'killed' (cut/copied) text. For example, M-2 C-y will retrieve
the second last one.

Unfortunately, for most people it's quite hard to remember what was 'killed'
and when and in what order… Those people can of course use the menu
(Edit/Paste from kill menu), but that is not always so convenient, requires
mousing around etc.

Edit: As Anynomous mentions in the comments, one can of course use M-y to
circle through the candidates. This is quite
useful, esp. when you have only a few items in the ring. Note, this command
only works just after a 'yank' (C-y).

browse-kill-ring

Instead, using the handy browse-kill-ring extension, you can open a buffer
which lists the contents of the kill ring, and you can move your cursor to the
desired item and insert it.

Installation in simple; first get the browse-kill-ring package from EmacsWiki, or, alternatively, Debian/Ubuntu users can install the
emacs-goodies-el-package.

Now, the M-y key binding will activate browse-kill-ring iff the normal behavior (see above) is not available, i.e., when the last command was not a
'yank'. You can also edit the kill-ring (press C-h m when in the
browse-kill-ring-buffer to see the available bindings).

a little pop-up menu

After which C-c y will show a little pop-up menu with the your kill-menu
entries. It does not seem to fully synchronize with the (possibly edited)
entries you get from browse-kill-ring, but it's a pretty neat way to
navigate through your kill-ring-buffers – if you don't have too many of them
(if so, you could customize the kill-ring-max variable).

2010-04-18

Syntax highlighting is useful when editing configuration files, programs and
so on, as it helps to prevent errors and makes it easier to quickly scan
documents.

Emacs supports syntax highlighting (font locking in emacs lingo) for many
different file types. For many common cases (e.g. editing for many programming
languages, org-mode), emacs' support goes much further than merely
colorizing keywords, and offers all kinds of 'magic' (auto-completion,
'electricity', special key bindings, …). For some other file types, at least
keywords are given some different color.

Still, there are files that are not recognized by emacs as having some
special format; these are displayed as plain text. This may be the case for
less-common configuration files, or your own specific formats.

Defining a full 'mode' for such file types can be a lot of work. Fortunately,
emacs offers a easier way: generic-mode. generic-mode defines a whole lot
of mode of modes for common formats, but also defines the
define-generic-mode macro to create your own modes.

Suppose we have a little language called foo; a typical foo-file might
look something like:

!! this is a comment
account=foo; !! another comment
user=jimmy;
password=$3cre7;

Using define-generic-mode, we can easily define a mode for this:

(require 'generic-x) ;; we need this
(define-generic-mode
'foo-mode ;; name of the mode to create
'("!!") ;; comments start with '!!'
'("account""user""password") ;; some keywords
'(("=" . 'font-lock-operator) ;; '=' is an operator
(";" . 'font-lock-builtin)) ;; ';' is a a built-in
'("\\.foo$") ;; files for which to activate this mode
nil ;; other functions to call
"A mode for foo files";; doc string for this mode
)

2010-04-04

A popular way to customize emacs is changing its color scheme, as already
discussed color theming. Until recently, I was using an evolved version of the
color theme presented there, 'djcb-dark'. It works for me but, admittedly,
it's a bit ugly.

But recently, in a post to the Wanderlust mailing list, someone mentioned a
color theme called Zenburn. Zenburn started its life as a color scheme for
vim, around 2002. The explicit goal was to have a pleasant theme that is
light on the eyes, and allows you to stay 'in the zone' for long stretches of
time. People liked it, and version for many other programs were made,
including emacs.

I've been using Zenburn for the last few weeks, and I really like it. I used
to think that 'low-contrast' would mean that things are not really clear; but
the opposite seems true. Anyway, the screen shot says more than a thousand
words I suppose…

Zenburn-for-emacs (written by Daniel Brockman) can be found at the link
above. I've sent my updates to him of course, but as it may take a while for
the 'official' version to be updated, I've put my version on
Emacswiki: ZenburnColorTheme. The changes are the support for Wanderlust,
hi-line (for highlighting the current line) , magit and elscreen; also,
I made selected (eh, transiently marked regions) not loose their foreground
color.

Note, the theme is not yet part of the color-theme package, but does require
it.